Many types of microphones have a diaphragm that forms a variable capacitor with a stationary member. During use, an incident audio signal causes the diaphragm to move relative to the stationary member. Consequently, this movement changes the capacitance of the variable capacitor to produce an electronic signal representing the incident audio signal. Eventually, this electronic signal may be processed to reproduce the incident audio signal on a speaker.
Some microphones have a diaphragm that is movably connected with its underlying stationary member by means of a plurality of springs. For example, U.S. Pat. No. 5,146,435 shows such a microphone. Unlike microphones having diaphragms connected to the stationary member in a drum-like manner, this type of microphone is more prone to breaking due to the stresses concentrated in the springs. Specifically, rather than distributing the force around an entire peripheral connecting member, a spring-based microphone concentrates forces on relatively small areas (i.e., on the springs). As a result, when subjected to relatively high force events, such as high mechanical and/or acoustic shock events (e.g., door slam or jet engine), one or more springs can break, thus rendering the microphone unusable.
One solution to this problem is to use the drum-like diaphragm approach. Although it may be more robust, however, a drum-like diaphragm approach may not be a desirable configuration for other design reasons (e.g., sensitivity concerns).